Interlocking system for railroads



Sept. 10,1935.

A. LANGDON 2,013,987

INTERLOCKING SYSTEM FOR RAILROADS Filed Nov. 11, 1951 INVENTOR ATTORNEY Patented Sept. 10, 1935 UNITED STTES ATE? OFFEQE Andrew Langdon, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application November 11, 1931, Serial No. 574,302

15 Claims.

This invention relates in general to interlocking systems for railways, and has more particular reference to a system of this character wherein. a single device is protected against misuse by means of a time measuring device, arranged to measure, respectively, different lengths of time, so as to give lockings of different durations.

In interlocking systems and the like, it may occur that a signal after being put to clear may then be changed to stop preparatory to moving a track switch or the like. Obviously, if an approaching train be proceeding fast enough, or is near enough to the switch at the time the signal is put to stop, the switch may be thrown under the train, or the train proceeding at a fast rate may be forced to take a diverging route at too great a speed for safety; in all event making for a dangerous condition.

To prevent such a contingency, it is desirable to provide means requiring a given lapse of time after a signal is put to stop, before control of a track switch or the like is given to the operator particularly if a train be approaching.

With the above and other objects in view, it is proposed, in accordance with this invention,

to provide a timing means of a thermal character, arranged to measure difierent lengths of time during which control of a track switch, for example, is withheld from an operator subsequent to his placing a signal at stop, with the different times automatically determined and made effective depending upon signal aspects, or the like.

The longer time employed is obtained by inserting an additional resistance in series with a heating element on the relay while the shorter time is obtained by cutting out this additional resistance, and further, by energizing a return winding of the relay whereby the relay is driven back to normal position instead of being allowed to cool back to normal.

Further objects, purposes and characteristic features of the present invention will appear as the description progresses, reference being made to the accompanying drawing, showing, solely by Way of example, and in no manner whatsoever in limiting sense, one form which the invention can assume. In the drawing:

The single figure of drawing is a wholly diagrammatic view showing one form of this invention.

Referring now to the drawing, there is here shown a stretch of track I, divided into signal blocks A, B and C by usual insulating joints 2, and having a diverging route D, controlled by a usual track switch TS. The blocks A, B and C are provided with usual track relays T T and T respectively and track batteries 2 At the entrance to block B, eastbound trafiic being considered, is a distant signal S having a signal blade which can assume clear, caution, 5 and stop positions, and, although shown as of the semaphore type, it can equally well be of any other usual, or desired, type.

At the entrance to the block C, from which block the diverging route D branches out, is posil0 tioned a home signal S having an upper signal blade S A, and a lower signal blade S 13, the upper blade controlling traflic over the main line, and the lower blade controlling traffic over the diverging route. 15

The signal S is controlled by signal levers S LB and S LA which can be placed by an operator either in normal or in reversed position, N and R, respectively. These signals S and S can be of the semi-automatic type and be jointly 20 controlled by traffic, in an automatic manner, and by the said signal levers, controlled by an operator.

The distant signal S and the home signal S are interlocked in any usual manner, (it being 25 deemed unnecessary for the purpose of this invention to describe or show it) so that signal S moves to proceed when blade S A moves to proceed, or to caution. S goes to caution when S B moves to caution, and S goes to caution 30 when both of the arms of S go to stop. The signal S of course, automatically goes to stop upon occupancy of block B.

A look relay L, is employed in this system, and is arranged to lock up the track switch TS, when 35 the relay is de-energized, in such a manner that the switch cannot be moved. It thus is necessary, in order for an operator to move the track switch TS, that the lock relay L first be energized and also that contact finger 32 of relay T be in attracted position as Will be later explained.

Employed in this system is a timing means, comprising a thermal relay TR, which has a fixed front contact 3, and a fixed back contact 4, with corresponding movable front and back contacts 45 5 and 6, suitably mounted to operate as a unit, on heating of the operating winding OW, to make up the front contacts 35, and break the back contacts 4-45, and to return to make up the back contacts 46, and break the front contacts 3-5, 50 upon the operating winding OW cooling down sufficiently. If a resistance r, be inserted in the energizing circuit for operating winding OW, an increased ime is required for operating the relay P0 QlQse its front contacts. 55

The relay also includes a restoring winding RW, which, when energized, drives the relay back to make up its back points 4-6, to thereby restore the relay to its normal position more rapidly than when the relay is allowed merely to cool back to its normal position. This relay TR is of the type shown and described in the application of J. E. Willing, Ser. No. 551,931, filed July 20, 1931.

The various parts of the system just described, are shown in their normal positions, wherein the signals are set for through traffic over the main line, with the track switch normal. Under these conditions, lock relay L is maintained energized, through a circuit including one terminal of a source of energy, contact finger I and front point of relay T contact finger 8 and front point of relay T contact finger 9 and front point of relay AS, contact fingers 6-4 of relay TR in closed position, relay L, and contact finger I0 and front point of relay S, to the other terminal of a source of energy.

Thus with relays T T AS, and S in energized positions, relay L is energized, andthe track switch is unlocked. The holding circuit for relay S, under the above conditions, includes contact finger I and front point of relay T contact finger 8 and front point of relay T contact finger 9 and front point of relay AS, wire ST, winding OW, contact finger H and front point of relay S, and the winding of relay S, which relay S has a high enough resistance to prevent defective energization of operating winding OW.

Thus it appears that when neither of the approach blocks A, B, is occupied, a stick circuit for relay S is maintained independently of the operation of relay TR, and with S up, relay L is held up, to unlock the. track switch so that the route can be changed to a turn-out route by moving signal lever S LA to normal and then immediately moving the track switch TS to reverse without the interposition of any timing delay therebetween. This is as it should be, since there is no danger to the approaching train which has not reached the approach block A at the time the route is changed.

Assume, however, that at the time the route is to be changed from main line to siding, a train is occupying either or both of the blocks A, B. In such circumstances, one or the other, or both, of the track relays, T and T will be de-energized to thereby break the energizing circuit for relay L, and for relay S, and lock up the track switch TS until relay L is energized.

Furthermore, an energizing circuit for relay AS, which includes contact finger 30 and front point of relay T and contact finger 3| and front point of relay T is broken, and under the conditions assumed, namely, that the track switch is at normal thus to position the switch contactor SC at normal, (as shown) relay AS remains deenergized.

Under the conditions assumed, on moving signal lever S LA to normal, energy is placed on the timing relay TR, through a circuit including contacts controlled by the signal levers S LA and S LB, wires l2 and I3, contact finger 9 and back point of relay AS, long time wire LT, resistance 1', operating winding OW, wires I 4 and I5, contact finger l I and back point of relay S, and wires [3 and H, thereby energizing relay TR through its operating winding, and including the resistance r, to thus give a relatively slow operation of the timing relay TR to energized position.

The resistance r is, of course, much less than that of relay S, and is of the order of one-half percent or so of the resistance of relay S. This resistance r however is sufiicient nevertheless to materially increase the operating time of winding OW over what it is with the resistance r omitted.

Upon relay TR making up its front points 3--5, a pick-up circuit is completed for relay S which includes, one terminal of a source of energy, wires I! and I8, winding of relay S, wires I9 and 20, contact fingers 35, resistance 7, wire LT, conl3 and l2, and contacts controlled by the two signal levers S LB and S LA in normal positions.

When once picked up relay S sticks up through a stick circuit including wires 1? and i8, winding of S, wires l9 and 2i, contact finger H and front point of S, wire l5, winding O'W, resistance r etc., as in the pick-up circuit traced just above.

The picking up of relay S breaks the energizing circuit for the operating winding OW of relay TR, which then cools down to slowly return to make up its back contacts 4S.

In this relay, the two windings OW and RW arearranged on two bi-metallic thermal elements oppositely placed with respect to each other, and connected together by a rigid member 27, whereby heating of one bi-metallic element moves the movable contacts 5 and 6 in one direction, and

heating of the other one moves the same contacts in the opposite direction as in application Ser. No. 551,931 referred to above.

With relay S energized, and relay TR in its normal position so as to make up contacts 5-45, an energizing circuit is completed for the lock relay L, which includes contacts controlled by the two signal levers S LA and S LB, wires l2 and l3, contact finger 9 and back point of relay AS, wire LT, resistance 2", contacts Z-6 of relay TR, wire 10 tact finger 9 and back point of relay AS, wires 28, relay L, wires 29 and 28, contact 10 and front point of relay S, and wires 25 and IT.

With relay L energized, if section C be unoccupied, control is given of the track switch TS, whereby it can be moved to turn-out position the track relay T having a contact 32 and front point included in the lock circuit, to provide usual approach looking for the track switch.

The time during which control of the track switch was withheld from the operator, after he had put the signal S A to stop, is measured by v the time required for the relay TR to make up its front contacts 35, plus the time required for this relay to return and make up its back contacts 4-6, and since the resistance r was inand the relay TR was allowed to cool back to normal, RW not having been energized, the long time was imposed as a condition for operation of the track switch TS.

If, instead of changing the route from main track to siding, the reverse is the case, and the route, set up for siding, is changed to main line, contact SC is in reverse to thereby energize relay AS through a circuit including SC, and the winding of AS, and as soon as the signal levers have been placed at normal to place both of the signals S B and S A at stop, relay AS is stuck up through a circuit including its winding, wire 33, contact finger 34 and front point of relay AS, wire 35,

cluded in series with the operating winding OW,

and the two signal repeater contacts 2A and 2B are already energized and there is no time interposed between placing the signals at stop, and gaining control of the track switch TS.

If, however, either or both of the blocks A, B are occupied, lock relay L is de-energized, and must be energized before control of the track switch isgiven to the operator.

With relay AS energized, energy from wire [3 is placed on Wire ST, for determining the short time delay, instead of on wire LT as described above. With energy on wire ST, relay TR has its operating winding OW energized without including resistance r in series therewith, whereby to cause relay TR to operate more speedily than before, to close its contacts 3--5 and, as described above, pick up, and then stick up, relay S.

Under the assumed conditions, relay TR does not cool back to make up its back contacts 4-6, but is driven back speedily by the return winding RW which is energized through a circuit including the two signal levers S LA and S LB, wires l2 and I3, contact finger 9 and front point of relay AS, wire ST, return winding RW, wire 22, contact finger 23 and front point of AS, wire 24, contact finger 25 and back point of relay L, wire 26, contact finger l0 and front point of relay S, and Wires l5 and I I.

As soon as relay TR makes up its back points 4-6, the pick-up circuit, traced above, for relay L is completed, whereupon relay L picks up to thereby break the energizing circuit for the winding RW, and control of the track switch TS is given.

It thus appears clear from the above that the route can be changed without the interposition of any delay between placing the signals at stop, and operating the track switch, provided neither of the blocks A, B is occupied. If, however, either of the blocks A, B is occupied, a time delay is interposed between placing the signals at stop and operating the track switch, and this time delay is either long or short, according to whether the change is from the main line to siding, or vice versa, and is determined by the condition of relay AS.

If the time is long, the resistancer is interposed in series with the winding OW, and the winding RW is not energized, while if the time is short, the resistance 1' is not included in the energizing circuit for the winding OW, and the return winding RW is energized, to thus drive relay TR back to normal position. By varying resistance r, any length of time for the long time can be obtained, While by using a drive back winding, as RW, the short time can be reduced to practical limits.

Furthermore, the resistance r can be omitted altogether, and the variation in time can be dependent entirely on the difference between driveback, and no drive-back.

Thus the difference between the long and the short time is produced by means of a resistance r, and drive-back or return winding RW, whereby any desired ratio of long to short time can be obtained, in one case in practice a ratio of approximately ten to one being desired, and obtained, the long time being in the order of two minutes and the short time being in the order of 15 seconds.

With the system as above described, if no approaching train is close enough to the track switch TS to be endangered by movement of the track switch, no time delay is imposed on the operation of the track switch.

If, however, an approaching train is within a dangerous distance of the track switch, and if the distant signal is at proceed, so that the approaching train is proceeding at a fast rate, and has not been warned of any necessity for stopping, the long time is interposed, whereby to allow the train either to pass beyond the track switch, or at least to enter the lock section C, to thereby safeguard itself by preventing a change in the position of the track switch.

If, new the approaching train is close enough to be endangered by a change in the position of the track switch, but the signal S is at caution, as is the case with the track switch set reverse, the approaching train is proceeding under control, at a low speed, and prepared to stop, and only a short time need be interposed before control of the track switch is given the operator. This short time is calculated to be suflicient for the approaching train either to stop before reaching the switch or to allow proceed onto the section C, and safeguard itself by locking up the switch, all as in the earlier filed Langdon application Ser. No. 550,130.

The above specific description of one form of system embodying the present invention, has been given solely by Way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously, this invention can assume many different physical forms, and is susceptible of numerous modifications, and all such forms and modifications, are intended to be covered by this application, as come within the scope of the appended claims.

Having described my invention, I now claim:

1. In an interlocking system, in combination with a stretch of track and a track switch, a lock circuit for the switch, a thermal relay required at times to operate for controlling the lock circuit, trafiic controlled means for determining the need for operation of the thermal relay for controlling the lock circuit, and means for varying the operating time of the thermal relay.

2. In an interlocking system, in combination with a stretch of track and a track switch, a lock circuit for the switch, a thermal relay at times required to operate for controlling the lock circuit, traiiic controlled means for determining said times, and means, controlled in accordance with traffic indications, for varying the operating time of the thermal relay when its operation is so required.

3. In combinaton, for use on railroads and the like, a trafiic controlling means, a lock circuit for the means, a thermal relay having an operating winding, a returning winding, and an insertable resistance, and arranged to control the lock circuit by a complete cycle operation of the thermal relay, and means for varying the time required for the cycle operation of the thermal relay to thereby vary the time control of the lock circuit.

4. In combination, for use or; railroads and the like, a, trafiic controlling means, a lock circuit for the means, a thermal relay having an operating winding,a returning winding,and an insertable resistance, and arranged to control the lock circuit, subject to traffic conditions, by a complete cycle operation of the thermal relay, and means for varying the time required for the cycle operation of the thermal relay to thereby vary the time control of the lock circuit.

5. In combination, for use on railroads and the cuit by a complete cycle operation of the thermal relay, and means for varying the time required for the cycle operation of the thermal relay by including or excluding the resistance in series with the operating winding, and by optionally energizing the returning winding, to thereby vary the time control of the lock circuit.

6. In combination, for use on railroads and the like, a trafiic controlling means, a lock circuit for the means, a thermal relay having an operating winding, a returning winding, and an insertable resistance, and arranged to control the lock circuit, subject to traific conditions, by a complete cycle operation of the thermal relay, and means for varying the time required for the cycle operation of the thermal relay to thereby vary the time control of the lock circuit, by including or excluding the resistance in series with the operating winding, and by optionally energizing the returning winding.

7 In combination, for use on railroads and the like, a traific controlling means, a lock circuit for the means, a thermal relay having an operating winding, a returning winding, and an insertable resistance, and arranged to control the lock circuit by a complete cycle operation of the thermal relay, and means for varying the time required for the cycle operation of the thermal relay to thereby vary the time control of the lock circuit, by including or excluding the resistance in series with the operating winding, and by optionally energizing the returning winding, the returning winding being employed when the resistance is not inserted in series with the operating winding.

8. In combination, for use on railroads and the like, a traffic controlling means, a lock circuit for the means, a thermal relay having an operating winding, a returning winding, and arranged to control the lock circuit, subject to trafiic conditions, by a complete cycle operation of the thermal relay, and means for varying the time required for the cycle operation of the thermal relay to thereby vary the time control of the lock circuit.

9. In combination, for use on railroads and the like, a traiiic controlling means, a lock circuit for the means, a thermal relay having an operating winding, a returning winding, and arranged to control the lock circuit, subject to traffic conditions, by a complete cycle operation of the thermal relay, and means for varying the time required for the cycle operation of the thermal relay to thereby vary the time control of the lock circuit, by optionally energizing the returning winding.

10. In combination, time measuring means including a thermal relay having a main thermal element and a compensating thermal element arranged to respond to the diiference of temperature between these elements and measuring time by a complete over and return movement of these elements, and means for causing said measuring means to define a short time by heating said main element to complete the over movement and by heating the compensating element to complete the return movement of said elements and to define the long time by heating the main element to complete the over movement and allow cooling of the main element to complete the return movement of said elements, and railway trafiic controlling apparatus controlled by said time measuring means.

11. In combination, a thermal relay having a main thermal element and a compensating thermal element, a stick relay, a traffic controlling device, means permitting control of said traffic controlling device only if said thermal relay assumes its normal condition and said stick relay assumes its energized condition, a pick-up circuit for said stick relay including a contact closed when said thermal relay assumes its abnormal condition, and means for causing said main thermal element to be heated to a temperature to cause said thermal relay to assume its abnormal condition and then allowed to cool to define a long time and for causing said main thermal element to be heated to a temperature to cause said thermal relay to assume its abnormal condition and thereafter causing said compensating element to be heated to cause said thermal relay to assume its normal condition to define a short time.

12. In combination, a thermal relay having a main thermal element and a compensating thermal element, a resistance unit, a stick relay,

a traffic controlling device, means permitting control of said traffic controlling device only if said thermal relay assumes its normal condition and said stick relay assumes its energised condition, a pick-up circuit for said stick relay including a contact closed when said thermal relay assumes its abnormal condition, and means for causing said main thermal element to be heated through circuit including said resistance unit to a temperature to cause said thermal relay to assume its abnormal condition and then allow it to cool to define a long time and for causing said main thermal element to be heated through a circuit excluding said resistance unit to a temperature to cause said thermal relay to assume its abnormal condition and thereafter causing said compensating element to be heated to cause said thermal relay to assume its normal condition to define a short time.

13. In combination, a railway track switch, signals for governing trafiic movement over said switch, a stick relay which must be energized to permit power operation of said switch, means for closing a pick-up circuit for said stick relay after a long period of delay following placing of said signals in the stop position with said track switch assuming the main track position and after a short period of delay following placing of said signals in the stop position, with said track switch assuming the side track position, an approach section in advance of said signals, and a 7 stick circuit for said stick relay including branches in multiple one branch of which includes a contact closed only if said approach section is unoccupied and the other branch of which includes contacts closed only if said signals are at stop, whereby clearing of one of said signals will not drop said stick relay unless there is a train in said approach section.

14. In combination, time measuring means including a thermal relay having a main thermal element and a compensating thermal element arranged to respond to the difierence of temperature between these elements and measuring time by a complete over and return movement of such elements, means for causing said measuring means to define a short time by heating the main element at a particular rate to complete the over movement and by heating the compensating element to complete the return movement, and to define the long time by heating the main element at a rate slower than said particular rate to complete the over movement and allow cooling of the main element to complete the return movement of said elements, and electro-responof said thermal relay and then energizing said returning circuit until the end of the return movement of the elements of said thermal relay, means for closing said lock circuit upon the closure of said control contact only after the elements of said thermal relay have completed a cycle of operation, and means for at times inserting a resistance in said operating circuit and for opening said returning circuit,

whereby the cycle of operation of the elements 1 of said thermal relay is prolonged.

ANDREW LANGDON. 

